Substrate support assembly

ABSTRACT

A substrate support assembly comprises a ceramic puck comprising a substrate receiving surface, and having embedded therein: (i) an electrode to generate an electrostatic force to retain a substrate placed on the substrate receiving surface; and (ii) a heater to heat the substrate, the heater comprising a plurality of spaced apart heater coils. A compliant layer bonds the ceramic puck to a base, the compliant layer comprising a silicon material. The base comprises a channel to circulate fluid therethrough, the channel having a channel inlet and a channel terminus.

CROSS-REFERENCE

This application is a continuation of U.S. Pat. No. 9,883,549,application Ser. No. 14/997,529, filed on Jan. 16, 2016, entitled“SUBSTRATE SUPPORT ASSEMBLY HAVING RAPID TEMPERATURE CONTROL”, whichclaims priority from U.S. Pat. No. 9,275,887 B2, filed on Jul. 14, 2007,entitled “SUBSTRATE PROCESSING WITH RAPID TEMPERATURE GRADIENT CONTROL”,which claims priority from U.S. Provisional Application Ser. No.60/832,545, filed Jul. 20, 2006, all of which are incorporated herein byreference in their entireties.

BACKGROUND

Embodiments of the present invention relate to apparatus for processinga substrate with temperature control across the substrate.

In the processing of substrates, such as semiconductors and displays, anelectrostatic chuck is used to hold a substrate in a chamber forprocessing a layer on the substrate. A typical electrostatic chuckcomprises an electrode covered by a ceramic. When the electrode iselectrically charged, electrostatic charges accumulate in the electrodeand substrate, and the resultant electrostatic force holds the substrateto the chuck. Typically, the temperature of the substrate is controlledby maintaining helium gas behind the substrate to enhance heat transferrates across the microscopic gaps at the interface between the back ofthe substrate and the surface of the chuck. The electrostatic chuck canbe supported by a base which has channels for passing a fluidtherethrough to cool or heat the chuck. Once a substrate is securelyheld on the chuck, process gas is introduced into the chamber and aplasma is formed to process the substrate. The substrate can beprocessed by a CVD, PVD, etch, implant, oxidation, nitridation, or othersuch processes.

In conventional substrate fabrication processes, the substrate ismaintained at a temperature during processing. Typically, the substrateis passed through a slit in the chamber by a wafer blade and depositedon lift pins which are extended through the body of the electrostaticchuck. The lift pins are then retracted back through the chuck todeposit the substrate on the surface of the chuck. The substrate quicklyrises in temperature to a preset temperature which is then maintainedsteady by heaters in the chuck or by the plasma formed in the chamber.The substrate temperature can be further controlled by the temperatureand flow rate of coolant passed through the channels of the base belowthe chuck which is used to remove heat from the chuck.

While conventional processing chambers are suitable for maintaining thesubstrate at a steady single temperature during processing, they do notallow rapid changing of the temperature of the substrate during a singleprocess cycle. In certain processes, it is desirable to rapidly ramp upor down the substrate temperature, to achieve a particular temperatureprofile during the process. For example, it can be desirable to haverapid changes in substrate temperature at different stages of an etchingprocess to allow etching of different materials on the substrate atdifferent substrate temperatures. At these different etching stages, theprocess gas provided to the chamber can also change in composition orhave the same composition. As another example, in etching processes,such a temperature profile may be useful to deposit sidewall polymer onthe sidewalls of the features being etched on the substrate, and laterin the same etching process, remove the sidewalk polymer by increasingthe temperature of the etching process, or vice versa. Similarly, indeposition processes, it may be desirable to have a first processingtemperature which is higher or lower than a second processingtemperature, for example, to initially deposit a nucleating layer on thesubstrate and then grow a thermally deposited layer on the substrate.Conventional substrate processing chambers and their internal componentsoften do not allow sufficiently rapid ramp up and down of substratetemperatures.

A further complication arises when, during processing, the substrate issubjected to non-uniform process conditions in a radial direction acrossthe substrate which can give rise to non-uniform, concentric processingbands. The non-uniform processing conditions can arise from thedistribution of gas or plasma species in the chamber, which often variesdepending on the location of the inlet and exhaust gas ports in thechamber. Mass transport mechanisms can also alter the rate of arrival ordissipation of gaseous species at different regions of the substratesurface. Non-uniform processing can also occur as a result ofnon-uniform heat loads in the chamber, arising for example, from thenon-uniform coupling of energy from a plasma sheath to the substrate orfrom radiant heat reflected from chamber walls. The processing bands andother variations across the substrate are undesirable as the electronicdevices being fabricated at different regions of the substrate, forexample, the peripheral and central substrate regions, end up withdifferent properties. Accordingly, it is desirable to reduce thevariations in processing rates and other process characteristics acrossthe substrate surface during processing of the substrate.

Thus it is desirable to have a process chamber and components that allowrapid temperature ramp up and down of the substrate being processed inthe chamber. It is further desirable to control temperatures atdifferent regions across the processing surface of the substrate toreduce the effect of non-uniform processing conditions across thesubstrate surface in the radial direction. It can also be desirable tocontrol the temperature profile across the substrate during processing.

SUMMARY

A substrate support assembly comprises a ceramic puck comprising asubstrate receiving surface, and having embedded therein: (i) anelectrode to generate an electrostatic force to retain a substrateplaced on the substrate receiving surface; and (ii) a heater to heat thesubstrate, the heater comprising a plurality of spaced apart heatercoils. A compliant layer bonds the ceramic puck to a base, the compliantlayer comprising a silicon material. The base comprises a channel tocirculate fluid therethrough, the channel having a channel inlet and achannel terminus.

DRAWINGS

These features, aspects, and advantages of the present invention willbecome better understood with regard to the following description,appended claims, and accompanying drawings, which illustrate examples ofthe invention. However, it is to be understood that each of the featurescan be used in the invention in general, not merely in the context ofthe particular drawings, and the invention includes any combination ofthese features, where:

FIG. 1 is a schematic side view of an embodiment of a substrateprocessing chamber with the electrostatic chuck;

FIG. 2 is a schematic sectional side view of an embodiment of anelectrostatic chuck;

FIG. 3 is a schematic bottom view of the electrostatic chuck of FIG. 1;

FIGS. 4A and 4B are schematic perspective views of the top (FIG. 4A) andbottom (FIG. 4B) of an embodiment of a base for the electrostatic chuck;

FIG. 5 is a schematic side view of an optical temperature sensor;

FIG. 6A is a schematic sectional side view of a ring assembly on theelectrostatic chuck of FIGS. 4A and 4B;

FIG. 6B is a detail of the ring assembly of FIG. 6A;

FIG. 7 is a graph depicting substrate temperature ramping over aninterval of time with a chiller at a constant temperature;

FIG. 8 is a graph depicting the temperature difference between theelectrostatic chuck and the chiller versus the percentage of heaterpower; and

FIG. 9 is a graph depicting the temperature ramping of the electrostaticchuck.

DESCRIPTION

An exemplary version of a chamber 106 capable of etching a substrate 25is schematically illustrated in FIG. 1. The chamber 106 isrepresentative of a Decoupled Plasma Source (DPS™) chamber which is aninductively coupled plasma etch chamber available from Applied MaterialsInc., Santa Clara, Calif. The DPS chamber may be used in the CENTURA®Integrated Processing System, commercially available from AppliedMaterials, Inc., Santa Clara, Calif. However, other process chambers mayalso be used in conjunction with the present invention, including, forexample, capacitively coupled parallel plate chambers, magneticallyenhanced ion etch chambers, inductively coupled plasma etch chambers ofdifferent designs, as well as deposition chambers. Although the presentapparatus and processes are advantageously used in a DPS chamber, thechamber is provided only to illustrate the invention, and should not beconstrued or interpreted to limit the scope of the present invention.

Referring to FIG. 1, a typical chamber 106 comprises a housing 114comprising enclosure walls 118 that include sidewalls 128, a bottom wall122, and a ceiling 130. The ceiling 130 may comprise a flat shape asshown, or a dome shape with a multi-radius arcuate profile as, forexample, described in U.S. Pat. No. 7,074,723, to Chinn et al., entitled“Method of Plasma Etching a Deeply Recessed Feature in a Substrate Usinga Plasma Source Gas Modulated Etchant System”, which is incorporated byreference herein in its entirety. The walls 118 are typically fabricatedfrom a metal, such as aluminum, or ceramic materials. The ceiling 130and/or sidewalls 128 can also have a radiation permeable window 126which allows radiation to pass through the chamber to monitor processesbeing conducted in the chamber 106. A plasma is formed in a process zonedefined by the process chamber 106, the substrate support and the domedceiling 130.

The substrate 25 is transported by a substrate transport 214 into thechamber 106 and held in the chamber 106 on a receiving surface 26 of asubstrate support comprising an electrostatic chuck 20 which in turnrests on a base 91. The electrostatic chuck 20 comprises a ceramic puck24 having a substrate receiving surface 26 which is the top surface ofthe ceramic puck 24, and serves to hold a substrate 25, as shown inFIGS. 1 and 2. The ceramic puck 24 also has a backside surface 28opposing the substrate receiving surface 26. The ceramic puck 24 has aperipheral ledge 29 having a first step 31 and a second step 33. Theceramic puck 24 comprises at least one of aluminum oxide, aluminumnitride, silicon oxide, silicon carbide, silicon nitride, titaniumoxide, zirconium oxide, and mixtures thereof. The ceramic puck 24 can beunitary monolith of ceramic made by hot pressing and sintering a ceramicpowder, and then machining the sintered form to form the final shape ofthe chuck 20.

It was determined that the thickness of the ceramic puck 24substantially affects the ability to rapidly ramp up and ramp down thetemperature of the substrate. If the ceramic puck 24 is too thick, theceramic puck 24 takes too long to ramp up and down in temperature,causing the temperature of the overlying substrate to take acorrespondingly excessive time to reach the desired set pointtemperature. Further, it was also determined that if the ceramic puck 24is too thin, it does not maintain the substrate at a steady statetemperature and results in substrate temperature fluctuations duringprocessing. Also, the thickness of the ceramic puck 24 affects operationof the electrode 36 which is embedded in the ceramic puck 24. If thethickness of the layer of the ceramic puck 24 directly above theembedded electrode 36 is too high, the electrode 36 does not effectivelycouple energy to the plasma formed in the process zone. On the otherhand, if the thickness of ceramic puck 24 about the electrode 36 is toothin, the RF voltage applied to the electrode 36 can discharge into theplasma creating arcing and plasma instabilities. Thus, the thickness ofthe ceramic puck 24 was precisely controlled to be a thickness of lessthan about 7 mm, for example, a thickness of from about 4 to about 7 mm;and in one version, the ceramic puck had a thickness of 5 mm. At thesethickness levels, the ceramic puck 24 allowed rapid increase anddecrease in the substrate temperature while reducing temperaturefluctuations during the process, and substantially without creatingplasma instabilities.

The electrode 36 embedded in the ceramic puck 24 is used to generate anelectrostatic force to retain a substrate placed on the substratereceiving surface 26, and optionally, to capacitively couple energy tothe plasma formed in the chamber 106. The electrode 36 is a conductor,such as a metal, and may be shaped as a monopolar or bipolar electrode.Monopolar electrodes comprise a single conductor and have a singleelectrical connection to an external electrical power source andcooperate with the charged species of the overlying plasma formed in achamber to apply an electrical bias across the substrate held on thechuck 20. Bipolar electrodes have two or more conductors, each of whichis biased relative to the other to generate an electrostatic force tohold a substrate. The electrode 36 can be shaped as a wire mesh or ametal plate with suitable cut-out regions. For example, an electrode 36comprising a monopolar electrode can be a single continuous wire meshembedded in the ceramic puck as shown. An embodiment of an electrode 36comprising a bipolar electrode can be a pair of filled-in C-shapedplates that face one another across the straight leg of the C-shape. Theelectrode 36 can be composed of aluminum, copper, iron, molybdenum,titanium, tungsten, or alloys thereof. One version of the electrode 36comprises a mesh of molybdenum. The electrode 36 is connected to aterminal post 58 which supplies electrical power to the electrode 36from an external electrode power supply 230, which can include a DCvoltage power supply, and optionally, an RF voltage power supply.

Optionally, a plurality of heat transfer gas conduits 38 a,b traversethe ceramic puck 24 and terminate in ports 40 a,b on the substratereceiving surface 26 of the chuck 20 to provide heat transfer gas to thesubstrate receiving surface 26. The heat transfer gas, which can be forexample, helium, is supplied below the substrate backside 34 to conductheat away from the overlying substrate 25 and to the receiving surface26 of the ceramic puck 24. For example, a first gas conduit 38 a can belocated to supply heat transfer gas to a central heating zone 42 a ofthe substrate receiving surface 26, and a second gas conduit 38 b can belocated to supply heat transfer gas to a peripheral heating zone 42 b ofthe substrate receiving surface 26. The central and peripheral heatingzones 42 a,b of the substrate receiving surface 26 of the ceramic puck24 allow corresponding portions of the substrate processing surface 44,for example, the overlying central and peripheral portions 46 a,b of thesubstrate 25 to be maintained at different temperatures to compensatefor non-uniform concentric processing bands that would otherwise occurin the substrate 25 due to corresponding non-uniform bands of processconditions which are different from one another.

The ceramic puck 24 also has an embedded heater to heat the substrate25. The heater comprises a plurality of heater coils 50, 52, forexample, a first heater coil 50 and a second heater coil 52, embedded inthe ceramic puck 24. The temperatures at the central and peripheralheating zones 42 a,b of the substrate receiving surface 26 of theceramic puck 24 are controlled using heater coils 50, 52 which areradially spaced apart and concentric about one another. In one version,the first heater coil 50 is located at a peripheral portion 54 b of theceramic puck 24 and the second heater coil 52 located at a centralportion 54 a of the ceramic puck 24. The first and second heater coils50, 52 allow independent control of the temperatures of the central andperipheral portions 54 a, 54 b of the ceramic puck 24, providing theability to independently control the temperatures of the heating zones42 a,b, to achieve different processing rates or characteristics acrossthe radial direction of the processing surface 44 of the substrate 25.As such, different temperatures can be maintained at the two heatingzones 42 a,b to affect the temperatures of the overlying central andperipheral portions 46 a,b of the substrate 25, thereby counteractingany variable gas species distribution or heat load occurring duringprocessing of the substrate 25. For example, when gas species at theperipheral portion 46 b of the processing surface 44 of the substrate 25are less active than those at the central portion 46 a, the temperatureof the peripheral heating zone 42 b is elevated to a higher temperaturethan the central heating zone 42 a to provide a more uniform processingrates or process characteristics across the processing surface 44 of thesubstrate 25. FIG. 8 demonstrates how the change in the substratetemperature is dependent upon the percentage of heater power supplied bythe inner and outer heating coils embedded in the chuck 20.

In one version, the first and second heater coils 50, 52 each comprisecircular loops of resistive heating elements that are arranged side byside, and can even be substantially in the same plane. For example, theheater coils 50, 52 can each be a continuous concentric loop thatgradually spirals radially inward in the body of the ceramic puck 24. Inone version, the heater comprises a coil having first loops spaced aparta first distance and second loops spaced apart a second distance that isgreater than the first distance. The second loops are positioned about alift pin hole in the puck. The heater coils 50, 52 can also be spiralcoils that spiral about an axis passing through the center of the coils,for example, like a light bulb filament, which are positioned inconcentric circles across the inside volume of the ceramic puck 24. Theresistive heating elements can be composed of different electricallyresistive materials, such as for example, tungsten or molybdenum.

The heater coils 50, 52 have an electrical resistance and operatingpower level that is selected to enhance the rate of ramping up and downthe temperature of the substrate 25. In one version, the heater coils50, 52 each comprise an electrical resistance sufficiently high torapidly rise to and maintain the substrate receiving surface 26 of theceramic puck 24 at temperatures of from about 80 to about 250° C. Inthis version, the electrical resistance of the heater coils is fromabout 4 to about 12 Ohms. In one example, the first heater coil 50 hasan electrical resistance of 6.5 ohm and the second heater coil 52 has anelectrical resistance inner of 8.5 ohm. In another version, the firstand second heater coils comprise a total resistance of less than 10ohms. In one version, the heater comprises a resistance of 8.5 ohms. Theheater coils 50, 52 are powered via independent terminal posts 58 a-dwhich extend through the ceramic puck 24.

In conjunction with the heater coils 50, 52, the pressure of heattransfer gas can also be controlled in the two heating zones 42 a,b torender the substrate processing rates more uniform across the substrate25. For example, the two zones 42 a,b can each be set to hold heattransfer gas at a different equilibrated pressure to provide differentheat transfer rates from the backside 34 of the substrate 25. This isaccomplished by supplying heat transfer gas at two different pressuresthrough the two gas conduits 38 a, 38 b, respectively, to exit at twodifferent locations of the substrate receiving surface 26.

The backside surface 28 of the ceramic puck 24 can have a plurality ofspaced apart mesas 30 as shown in FIG. 3. In one version, the mesas 30are cylindrical mounds that are separated from each other by a pluralityof gaps 32. In use, the gaps 32 are filled with a gas, such as air, toregulate the heat transfer rates from the backside surface 28 to theunderlying surface of the base. In one embodiment, the mesas 30 comprisecylindrical mounds, which can even be shaped as posts that extend upfrom the backside surface 28, the posts having a rectangular or circularcross-sectional shape. The height of the mesas 30 can be from about 10to about 50 microns, and the diameter of the mesas 30 can be from about500 to about 5000 microns. However, the mesas 30 can also have othershapes and sizes, for example, cones or rectangular blocks, or evenbumps of varying sizes. In one version, the mesas 30 are formed by beadblasting the backside surface 28 with a bead size that is suitablysmall, for example, in the tens of microns, to etch away by erosion thematerial of the backside surface 28 to form the shaped mesas 30 with theintervening gaps 32.

The electrostatic chuck 20 also includes an optical temperature sensor60 a,b that passes through holes 62 a,b in the ceramic puck 24 tocontact and accurately measure the temperatures of the overlying centraland peripheral portions 46 a,b of the substrate 25. A first sensor 60 ais positioned at the central heating zone 42 a of the ceramic puck 24 toread the temperature of the central portion 46 a of the substrate 25,and a second sensor 60 b is positioned at the peripheral heating zone 42b of the ceramic puck 24 to correspondingly read the temperature at theperipheral portion 46 b of the substrate 25. The optical temperaturesensors 60 a,b are positioned in the chuck 20 so that the tips 64 a,b ofthe sensors lies in a plane with the substrate receiving surface 26 ofthe ceramic puck 24, such that the sensor tips 64 a,b can contact thebackside 34 of the substrate 25 held on the chuck 20. The legs 66 a,b ofthe sensors 60 a,b extend vertically through the body of the ceramicpuck 24.

In one version, as shown in FIG. 5, each optical temperature sensor 60comprises a heat sensor probe 68 comprising a copper cap 70 shaped as aclosed off cylinder with a side 72 and a dome-shaped top 74 that servesas the tip 64. The copper cap 70 can be composed of oxygen free coppermaterial. A phosphorous plug 76 is embedded inside, and in directcontact with, the dome-shaped top 74 of the copper cap 70. Thephosphorous plug 76 embedded in the copper cap 70 provides quicker andmore sensitive thermal response for the heat sensing probe 68. The tip64 of the copper cap 70 is a dome-shaped top 74 to allow repeatedcontact with different substrates 25 without eroding or damaging thesubstrates. The copper cap 70 has a recessed groove 78 for receivingepoxy 79 to affix the cap 70 in the heat sensing probe 68.

The phosphorous plug 76 converts heat in the form of infrared radiationto photons which are passed though an optical fiber bundle 80. Theoptical fiber bundle 80 can be composed of borosilicate glass fibers.The optical fiber bundle 80 is encased by a sleeve 82, which in turn ispartially surrounded by a temperature isolation jacket 84 that serves toisolate the temperature sensor from the heat of the base that supportsthe ceramic puck. The sleeve 82 can be a glass tubing to provide betterthermal insulation from the surrounding structure, but can also be madefrom a metal such as copper. The temperature isolation jacket 84 may becomposed of PEEK, a polyetheretherketone, and can also be Teflon®(polytetrafluoroethylene) from Dupont de Nemours Co., Delaware.

A substrate support 90 comprising the electrostatic chuck 20 is securedto a coolant base 91 which is used to support and secure the chuck 20,as well as to cool the chuck (FIGS. 4A and 4B). The base 91 comprises ametal body 92 with a top surface 94 having a chuck receiving portion 96and peripheral portion 98. The chuck receiving portion 96 of the topsurface 94 is adapted to receive the backside surface 28 of the ceramicpuck 24 of the electrostatic chuck 20. The peripheral portion 98 of thebase 91 extends radially outward beyond the ceramic puck 24. Theperipheral portion 98 of the base 91 can be adapted to receive a clampring 100 which can be secured to the top surface of the peripheralportion of the base 91. The metal body 92 of the base 91 has a number ofpassages 102 running from a bottom surface 104 of the base 91 to the topsurface 94 of the base 91, to for example, hold the terminals 58 a-d orfeed gas to the gas conduits 38 a,b of the ceramic puck 24.

The base 91 has a coolant channel 110 comprising an inlet 95 and aterminus 97 to circulate coolant through the channel. The inlet 95 andterminus 97 of the coolant channel 110 can be positioned adjacent to oneanother when the coolant channel 110 loops back upon itself, as shown inFIG. 4B. The coolant may be fluid, such as water, or other suitable heattransfer fluid from a heat transfer fluid supply 220, which ismaintained at a preset temperature in any chiller (not shown), andpumped through the channel of the base 91. The base 91 with thecirculating cooling fluid serves as a heat exchanger to control thetemperatures of the chuck 20 to achieve desired temperatures across theprocessing surface 44 of the substrate 25. The fluid passed through thechannels 110 can be heated or cooled to raise or lower the temperatureof the chuck 20 and that of the substrate 25 held on the chuck 20. Inone version, the channels 110 are shaped and sized to allow fluid toflow through to maintain the base 91 at temperatures of from about 0 to120° C.

The chuck receiving portion 96 of the top surface 94 of the base 91comprises one or more grooves 108 a,b to retain and flow air across thebackside of the ceramic puck 24. In one embodiment, the chuck receivingportion 96 comprises a peripheral groove 108 a which cooperates with aplurality of mesas 30 on the backside surface 28 of a ceramic puck 24 tocontrol a rate of heat transfer from the peripheral portion 54 b of theceramic puck 24. In another embodiment, the chuck receiving surface ofthe base 91 comprises a peripheral groove 108 a to contain air about themesas 30 of the backside surface 28 of the ceramic puck 24. In yetanother embodiment, a central groove 108 b is used in conjunction withthe peripheral groove 108 a to also regulate heat transfer from thecentral portion 54 a of the ceramic puck 24.

The grooves 108 a,b in the top surface 94 of the base 91 cooperate withthe mesas 30 on the backside surface 28 of the ceramic puck 24 tofurther regulate the temperatures across the substrate processingsurface 44. The mesas 30 on the backside surface 28 of the ceramic puck24 can be distributed across the backside surface 28 in a uniform ornon-uniform pattern. The shape, size, and spacing of the mesas 30control the total amount of contact surface of the mesas 30 with the topsurface 94 of the base 91 thereby controlling the total heat conductionarea of the interface. When in a uniformly spaced apart pattern, thedistance between the mesas 30 as represented by the gaps 32 remainsubstantially the same, and in a non-uniform spacing, the gap distancevaries across the backside surface 28.

Optionally, the backside surface 28 of the ceramic puck 24 can have afirst array 39 of mesas 30 adjacent to the inlet 95 of the coolantchannel 110 in the base 91, and a second array 41 of the mesas 30 distalfrom the inlet 95 of the channel 110 or even adjacent to the terminus 97of the coolant channel 110, as shown in FIG. 3. The second array 41 ofmesas 30 has a different gap distance forming a different pattern thanthe first array 39 to regulate the heat transfer rates about the regionsadjacent to, and distal from the coolant channel 110. For example, aportion of the ceramic puck 24 overlying a segment of the coolantchannel 110 near the channel inlet 95 which receives fresh coolant isoften maintained at lower temperatures that the portion of the ceramicpuck 24 overlying a segment of the coolant channel 110 near the channelterminus 97. This is because the coolant warms up as it travels throughthe length of the channel 110 in the base 91 by capturing heat from theceramic puck 24. As result, the substrate 25 placed on the receivingsurface 26 of the ceramic puck 24 has a temperature profile with highertemperatures and regions overlying the coolant channel terminus 97relative to the temperatures of regions overlying the inlet 95. Thistemperature profile is compensated for by providing a first array 39 ofmesas 30 about the channel inlet 95 which are spaced apart at a firstgap distance, and a second array 41 of mesas 30 about the channelterminus 97 which are spaced apart at a second gap distance which isdifferent from the first distance. When the first distance is largerthan the second distance, the heat transfer rate from the portions ofthe substrate 25 directly overlying the first array 39 is lower than theheat transfer rate from portions of the substrate 25 directly overlyingthe second array 41. Consequently, heat is transferred away at a slowerrate from the first substrate regions than the rate of heat transferfrom the second substrate regions causing the first regions to becomewarmer than the second regions to compensate for and equalize thetemperature profile that would otherwise have occurred across thesubstrate surface 44 because of the coolant channel inlet 95 andterminus 97. In one example, the first array 39 of mesas 30 is spacedapart at a first distance of at least about 5 mm, while the second array41 of mesas 30 is spaced apart at a second distance of less than about 3mm.

The same temperature profile control can be obtained by changing thedimensions of the contact regions of first array 39 of mesas 30 relativeto the dimensions of the contact regions of the second array 41 of mesas30. For example, the first dimensions of the contact regions of firstarray 39 of mesas 30 can be less than about 2000 microns, while thecontact regions of the second array 41 of mesas 30 can be at least about3000 microns. The first and second dimensions can be a diameter of amesa 30 comprising a post shape. In one version, the first dimension isa diameter of 1000 microns and the second dimension is a diameter of4000 microns. The less the contact area, the higher the temperaturesacross the substrate processing surface 44. Also, air is providedbetween the mesas 30 and across the backside surface 28 to serve as afurther temperature regulator.

Another factor that affects the ability to rapidly ramp the substrate upand down in temperature is the nature of the thermal interface betweenthe ceramic puck 24 and the base 91. An interface polymer materialhaving a good thermal conductivity is desirable at the interface toallow heat to be easily removed from the ceramic puck 24 by the coolanttraversing through the base 91. In addition, it is desirable for theinterface to be compliant because the high temperature differentialbetween the ceramic puck 24 and the coolant base 91 results in thermalexpansion stresses which can cause cracking or other thermal stressinduced damage of the ceramic puck 24. In one version, a compliant layer61 comprising a polymer is used to bond the back surface of the ceramicpuck 24 to the front surface of the base 91. The compliant layer 61 isfabricated to provide good thermal conductivity while still beingsufficiently compliant to absorb the high thermal stresses. In oneversion, the compliant layer 61 comprises silicon with embedded aluminumfibers. The silicon material provides good compliance while still havinga reasonable thermal conductivity. The thermal conductivity of thesilicon material is enhanced with the embedded aluminum fibers. Inanother version, the compliant layer 61 comprises acrylic having anembedded wire mesh. Again, the acrylic polymer is selected to providecompliance with thermal stresses while the embedded wire mesh enhancesthe thermal conductivity of the structure.

The base 91 further comprises an electrical terminal assembly 120 forconducting electrical power to the electrode 36 of the electrostaticchuck 20 and the first and second heater coils 50, 52, as shown in FIG.6A. The electrical terminal assembly 120 comprises a ceramic insulatorjacket 124. The ceramic insulator jacket 124 can be for example,aluminum oxide. A plurality of terminal posts 58, 58 a-d are embeddedwithin the ceramic insulator jacket 124. The terminal posts 58, 58 a-dsupply electrical power to the electrode 36 and heater coils 50, 52 ofthe electrostatic chuck 20. For example, the terminal posts 58, 58 a-dcan include copper posts.

A ring assembly 170 can also be provide to reduce the formation ofprocess deposits on, and protect from erosion, peripheral regions of thesubstrate support 90 comprising the electrostatic chuck 20 supported bythe base 91, as shown in FIGS. 6A and 6B. The ring assembly 170comprises a clamp ring 100 that is secured to the peripheral portion 98of the top surface 94 of the base 91 with securing means such as screwsor bolts (not shown). The clamp ring 100 has a lip 172 which extendstransversely and radially inward, a top surface 174 and an outer sidesurface 176. The lip 172 has an undersurface 173 which rests on thefirst step 31 of the peripheral ledge 29 of the ceramic puck 24 to forma gas-tight seal with the ceramic puck 24, a top surface 174 and anouter side surface 176. In one version, the undersurface 173 comprises apolymer layer 179, for example comprising polyimide, to form a goodgas-tight seal. The clamp ring 100 is fabricated from a material thatcan resist erosion by plasma, for example, a metallic material such asstainless steel, titanium or aluminum; or a ceramic material, such asaluminum oxide.

The ring assembly also includes an edge ring 180 comprising a band 182having a foot 184 which rests on the top surface 174 of the clamp ring100. The edge ring also has an annular outer wall enclosing the outerside surface 176 of the clamp ring 100 which would otherwise be exposedto the processing environment to reduce or even entirely precludedeposition of sputtering deposits on the clamp ring 100. The edge ring180 also comprises a flange 190 covering the second step 33 of theperipheral ledge 29 of the ceramic puck 24 to form a seal with anoverlying edge of a substrate retained on the receiving surface of theceramic puck 24. The flange 190 comprises a projection 194 thatterminates below an overhanging edge 196 of the substrate 25. The flange190 defines an inner perimeter of the ring 180 that surrounds theperiphery of the substrate 25 to protect regions of the ceramic puck 24that are not covered by the substrate 25 during processing. The clampring 100 and the edge ring 180 of the ring assembly 170 cooperate toreduce the formation of process deposits on, and protect from erosion,the electrostatic chuck 20 supported on the base 91 during theprocessing of a substrate 25 in the process chamber 106. The edge ring180 protects the exposed side surfaces of the substrate support 90 toreduce erosion by the energized plasma species. The ring assembly 170can be easily removed to clean deposits from the exposed surfaces of therings 100, 180 so that the entire substrate support 90 does not have tobe dismantled to be cleaned. The edge ring 180 comprises a ceramic, suchas for example, quartz.

In operation, process gas is introduced into the chamber 106 through agas delivery system 150 that includes a process gas supply 204comprising gas sources that each feed a conduit 203 having a gas flowcontrol valve 158, such as a mass flow controller, to pass a set flowrate of the gas therethrough. The conduits feed the gases to a mixingmanifold (not shown) in which the gases are mixed to form a desiredprocess gas composition. The mixing manifold feeds a gas distributor(not shown) having gas outlets in the chamber 106. The gas outlets maypass through the chamber sidewalls 128 terminate about a periphery ofthe substrate support 90 or may pass through the ceiling 130 toterminate above the substrate 25. Spent process gas and byproducts areexhausted from the chamber 106 through an exhaust system 210 whichincludes one or more exhaust ports 211 that receive spent process gasand pass the spent gas to an exhaust conduit in which there is athrottle valve 178 to control the pressure of the gas in the chamber106. The exhaust conduit feeds one or more exhaust pumps 218. Theexhaust system 210 may also contain an effluent treatment system (notshown) for abating undesirable gases that are exhausted.

The process gas is energized to process the substrate 25 by a gasenergizer 208 that couples energy to the process gas in a process zoneof the chamber 106 or in a remote zone upstream from the chamber 106(not shown). By “energized process gas” it is meant that the process gasis activated or energized to form one or more of dissociated gasspecies, non-dissociated gas species, ionic gas species, and neutral gasspecies. In one version, the gas energizer 208 comprises an antenna 186comprising one or more inductor coils 188 which may have a circularsymmetry about the center of the chamber 106. Typically, the antenna 186comprises solenoids having from about 1 to about 20 turns with a centralaxis coincident with the longitudinal vertical axis that extends throughthe process chamber 106. A suitable arrangement of solenoids is selectedto provide a strong inductive flux linkage and coupling to the processgas. When the antenna 186 is positioned near the ceiling 130 of thechamber 106, the adjacent portion of the ceiling 130 may be made from adielectric material, such as silicon dioxide, which is transparent to RFor electromagnetic fields. The antenna 186 is powered by an antennacurrent supply (not shown) and the applied power is tuned by an RF matchnetwork. The antenna current supply provides, for example, RF power tothe antenna 186 at a frequency of typically about 50 KHz to about 60MHz, and more typically about 13.56 MHz; and at a power level of fromabout 100 to about 5000 Watts.

When an antenna 186 is used in the chamber 106, the walls 118 include aceiling 130 made from a induction field permeable material, such asaluminum oxide or silicon dioxide, to allow the inductive energy fromthe antenna 186 to permeate through the walls 118 or ceiling 130. Asuitable semiconductor material is doped silicon. For doped siliconsemiconducting ceilings, the temperature of the ceiling 130 ispreferably held in a range at which the material provides semiconductingproperties and in which the carrier electron concentration is fairlyconstant with respect to temperature. For doped silicon, the temperaturerange may be from about 100 K (below which silicon begins to havedielectric properties) to about 600 K (above which silicon begins tohave metallic conductor properties).

In one version, the gas energizer 208 is also a pair of electrodes (notshown) that may be capacitively coupled to provide a plasma initiatingenergy to the process gas or to impart a kinetic energy to energized gasspecies. Typically, one electrode is in the support 90 below thesubstrate 25 and the other electrode is a wall, for example, thesidewall 128 or ceiling 130, of the chamber 106. For example, theelectrode may be a ceiling 130 made of a semiconductor that issufficiently electrically conductive to be biased or grounded to form anelectric field in the chamber 106 while still providing low impedance toan RF induction field transmitted by the antenna 186 above the ceiling130. A suitable semiconductor comprises silicon doped to have anelectrical resistivity of, for example, less than about 500 Ω-cm at roomtemperature. Generally, the electrodes may be electrically biasedrelative to one another by a biasing voltage supply (not shown) thatprovides an RF bias voltage to the electrodes to capacitively couple theelectrodes to one another. The applied RF voltage is tuned by an RFmatch network. The RF bias voltage may have frequencies of about 50 kHzto about 60 MHz, or about 13.56 MHz, and the power level of the RF biascurrent is typically from about 50 to about 3000 watts.

The chamber 106 may be operated by a controller 300 comprising acomputer that sends instructions via a hardware interface to operate thechamber components, including the substrate support 90 to raise andlower the substrate support 90, the gas flow control valves 158, the gasenergizer 208, and the throttle valve 178. The process conditions andparameters measured by the different detectors in the chamber 106, orsent as feedback signals by control devices such as the gas flow controlvalves 158, pressure monitor (not shown), throttle valve 178, and othersuch devices, are transmitted as electrical signals to the controller300. Although, the controller 300 is illustrated by way of an exemplarysingle controller device to simplify the description of presentinvention, it should be understood that the controller 300 may be aplurality of controller devices that may be connected to one another ora plurality of controller devices that may be connected to differentcomponents of the chamber 106; thus, the present invention should not belimited to the illustrative and exemplary embodiments described herein.

The controller 300 comprises electronic hardware including electricalcircuitry comprising integrated circuits that is suitable for operatingthe chamber 106 and its peripheral components. Generally, the controller300 is adapted to accept data input, run algorithms, produce usefuloutput signals, detect data signals from the detectors and other chambercomponents, and to monitor or control the process conditions in thechamber 106. For example, the controller 300 may comprise a computercomprising (1) a central processing unit (CPU), such as for example aconventional microprocessor from INTEL corporation, that is coupled to amemory that includes a removable storage medium, such as for example aCD or floppy drive, a non-removable storage medium, such as for examplea hard drive, ROM, and RAM; (ii) application specific integratedcircuits (ASICs) that are designed and preprogrammed for particulartasks, such as retrieval of data and other information from the chamber106, or operation of particular chamber components; and (iii) interfaceboards that are used in specific signal processing tasks, comprising,for example, analog and digital input and output boards, communicationinterface boards, and motor controller boards. The controller interfaceboards, may for example, process a signal from a process monitor andprovide a data signal to the CPU. The computer also has supportcircuitry that include for example, co-processors, clock circuits,cache, power supplies and other well known components that are incommunication with the CPU. The RAM can be used to store the softwareimplementation of the present invention during process implementation.The instruction sets of code of the present invention are typicallystored in storage mediums and are recalled for temporary storage in RAMwhen being executed by the CPU. The user interface between an operatorand the controller 300 can be, for example, via a display and a datainput device, such as a keyboard or light pen. To select a particularscreen or function, the operator enters the selection using the datainput device and can review the selection on the display.

The data signals received and evaluated by the controller 300 may besent to a factory automation host computer. The factory automation hostcomputer may comprise a host software program that evaluates data fromseveral systems, platforms or chambers 106, and for batches ofsubstrates 25 or over an extended period of time, to identifystatistical process control parameters of (i) the processes conducted onthe substrates, (ii) a property that may vary in a statisticalrelationship across a single substrate, or (iii) a property that mayvary in a statistical relationship across a batch of substrates. Thehost software program may also use the data for ongoing in-situ processevaluations or for the control of other process parameters. A suitablehost software program comprises a WORKSTREAM™ software program availablefrom aforementioned Applied Materials. The factory automation hostcomputer may be further adapted to provide instruction signals to (i)remove particular substrates 25 from the etching sequence, for example,if a substrate property is inadequate or does not fall within astatistically determined range of values, or if a process parameterdeviates from an acceptable range; (ii) end etching in a particularchamber 106, or (iii) adjust process conditions upon a determination ofan unsuitable property of the substrate 25 or process parameter. Thefactory automation host computer may also provide the instruction signalat the beginning or end of etching of the substrate 25 in response toevaluation of the data by the host software program.

In one version, the controller 300 comprises a computer program that isreadable by the computer and may be stored in the memory, for example onthe non-removable storage medium or on the removable storage medium. Thecomputer program generally comprises process control software comprisingprogram code to operate the chamber 106 and its components, processmonitoring software to monitor the processes being performed in thechamber 106, safety systems software, and other control software. Thecomputer program may be written in any conventional programminglanguage, such as for example, assembly language, C++, Pascal, orFortran. Suitable program code is entered into a single file, ormultiple files, using a conventional text editor and stored or embodiedin computer-usable medium of the memory. If the entered code text is ina high level language, the code is compiled, and the resultant compilercode is then linked with an object code of pre-compiled libraryroutines. To execute the linked, compiled object code, the user invokesthe object code, causing the CPU to read and execute the code to performthe tasks identified in the program.

In operation, using the data input device, for example, a user enters aprocess set and chamber number into the computer program in response tomenus or screens on the display that are generated by a processselector. The computer program includes instruction sets to control thesubstrate position, gas flow, gas pressure, temperature, RF powerlevels, and other parameters of a particular process, as well asinstructions sets to monitor the chamber process. The process sets arepredetermined groups of process parameters necessary to carry outspecified processes. The process parameters are process conditions,including without limitations, gas composition, gas flow rates,temperature, pressure, and gas energizer settings such as RF ormicrowave power levels. The chamber number reflects the identity of aparticular chamber when there are a set of interconnected chambers on aplatform.

A process sequencer comprises instruction sets to accept a chambernumber and set of process parameters from the computer program or theprocess selector and to control its operation. The process sequencerinitiates execution of the process set by passing the particular processparameters to a chamber manager that controls multiple tasks in achamber 106. The chamber manager may include instruction sets, such asfor example, substrate positioning instruction sets, gas flow controlinstruction sets, gas pressure control instruction sets, temperaturecontrol instruction sets, gas energizer control instruction sets, andprocess monitoring instruction sets. While described as separateinstruction sets for performing a set of tasks, each of theseinstruction sets can be integrated with one another or may beover-lapping; thus, the chamber controller 300 and the computer-readableprogram described herein should not be limited to the specific versionof the functional routines described herein.

The substrate positioning instruction sets comprise code for controllingchamber components that are used to load a substrate 25 onto thesubstrate support 90, and optionally, to lift a substrate 25 to adesired height in the chamber 106. For example, the substratepositioning instruction sets can include code for operating a transferrobot arm (not shown) which transfers a substrate into the chamber, forcontrolling lift pins (not shown) which are extended through holes inthe electrostatic chuck, and for coordinating the movement of the robotarm with the motion of the lift pins.

The program code also include temperature control instruction sets toset and control temperatures maintained at different regions of thesubstrate 25, by for example, independently applying differentelectrical power levels to the first and second heater coils 50, 52 inthe ceramic puck 24 of the chuck 20. The temperature control instructionsets also adjust the flow of heat transfer gas from a heat transfer gassupply 222 that is passed through the conduits 38 a,b.

The temperature control instruction sets also comprise code to controlthe temperature and flow rate of coolant fluid passed through thecoolant channels 110 of the base 91. In one version, the temperaturecontrol instruction set comprises code to increase a coolant temperaturein the coolant base 91 to a higher level, for at least about one second,from an earlier a lower level, immediately prior to ramping up the powerlevel applied to the heater. This allows coolant at a higher temperatureto be circulated in the coolant channels 110 of the base 91 just beforethe heater increases temperature to reduce the heat flow from theceramic puck 24 to the base 91 when the heater does eventually rise intemperature, thereby, effectively increasing the temperature ramp uprate of the substrate 25. Conversely, the program code includesinstruction sets to decrease the coolant temperature, for example, atleast by 10° C. and the coolant base 91 to a lower level prior toramping down the power level applied to the heater to accelerate therate at which heat is transferred from the substrate 25 when thesubstrate temperature is ramped down. The temperature versus time graphin FIG. 7 depicts the temperature ramp rate for a substrate 25 rampedfrom 45° C. to 75° C. with the coolant base 91 maintained at 5° C. FIG.9 depicts the rapid change in substrate temperature through the graph ofthe temperature ramping of the electrostatic chuck 20 which holds andimparts heat to the substrate 25. The substrate 25 maintains the sametemperature as the electrostatic chuck 20 by the use of backside heliumpressure. The graph demonstrates how the electrostatic chuck 25 isramped up and ramped down over a given interval of time. The two steephills 291, 293 on the graph indicate the fast ramping up and rampingdown of the temperature, respectively. Such fast temperature ramping ofthe electrostatic chuck 20 allows for rapid changes in the substratetemperature, thus enabling etching of previously incompatible materialssuch as Poly-Si and WSIX.

A process feedback control instruction sets can serve as a feedbackcontrol loop between a temperature monitoring instruction sets whichreceives temperature signals from the optical temperature sensors 60 a,bto adjust the power applied to the chamber components, such as theheater coils 50, 52 from the outer and inner heater power supplies 226,228, respectively, the flow of heat transfer gas through the conduits 38a,b, flow of fluid through the channels 110 of the base 91, and coolanttemperature.

The gas flow control instruction sets comprise code for controlling theflow rates of different constituents of the process gas. For example,the gas flow control instruction sets may regulate the opening size ofthe gas flow control valves 158 to obtain the desired gas flow ratesfrom the gas conduits 203 into the chamber 106. In one version, the gasflow control instruction sets comprise code to set a first volumetricflow rate of a first gas and a second volumetric flow rate of a secondgas to set a desired volumetric flow ratio of the first process gas tothe second process gas in the process gas composition.

The gas pressure control instruction sets comprise program code forcontrolling the pressure in the chamber 106 by regulating open/closeposition of the throttle valve 178. The temperature control instructionsets may comprise, for example, code for controlling the temperature ofthe substrate 25 during etching or code for controlling the temperatureof walls of the chamber 106, such as the temperature of the ceiling. Thegas energizer control instruction sets comprise code for setting, forexample, the RF power level applied to the electrodes or to the antenna186.

While described as separate instruction sets for performing a set oftasks, it should be understood that each of these instruction sets canbe integrated with one another, or the tasks of one set of program codeintegrated with the tasks of another to perform the desired set oftasks. Thus, the controller 300 and the computer program describedherein should not be limited to the specific version of the functionalroutines described herein; and any other set of routines or mergedprogram code that perform equivalent sets of functions are also in thescope of the present invention. Also, while the controller isillustrated with respect to one version of the chamber 106, it may beused for any chamber described herein.

The present apparatus and process provides significant benefits byallowing very rapid changes in temperature of the substrate 25 betweendifferent steps of a process performed on the substrate 25 and thechamber 106. Such rapid temperature changes increase the speed at whichan etching process having multiple steps can be performed. The presentsystem also allows accurate reproduction of a temperature ramp up andramp down profile desirable for a particular process, such as an etchingprocess having multiple etching stages which are required for theetching of different materials or layers on the substrate 25. Yetanother advantage is that the present apparatus allows maintaining thesubstrate 25 at temperatures which are significantly higher than thetemperature of the coolant base 91, which in turns allows theapplication of higher plasma power to the substrate 25 without anysubstrate temperature drift during the process. The large temperaturedifference between the substrate 25 and the coolant base 91 also allowsgood temperature differences between the zones 42 a,b of the substrate25, thereby compensating for varying annular process conditions acrossthe substrate surface.

Although the present invention has been described in considerable detailwith regard to certain preferred versions thereof, other versions arepossible. For example, the apparatus components such as the substratesupport, coolant base, and temperature sensor can be used for otherchambers and for other processes, than those described herein.Therefore, the appended claims should not be limited to the descriptionof the preferred versions contained herein.

What is claimed is:
 1. A substrate support assembly comprising: (a) aceramic puck comprising: (i) a substrate receiving surface; (ii) anelectrode to generate an electrostatic force to retain a substrateplaced on the substrate receiving surface; (iii) a plurality of spacedapart resistive heating elements; and (iv) a backside surface having aplurality of shaped mesas that are spaced apart from one another tocontact a base, the shaped mesas comprising posts, cones, rectangularblocks, or cylindrical mounds, and wherein the shaped mesas include anarray of first mesas that are adjacent to a channel inlet which isadjacent to a periphery of the base, and an array of second mesas thatare adjacent to a channel terminus, and comprising at least one of: (1)the first mesas are spaced apart a first distance that is larger than asecond distance between the second mesas; and (2) the first mesas have afirst contact region that is smaller than a second contact region of thesecond mesas; (b) a compliant polymer layer bonding the ceramic puck tothe base, the compliant polymer layer comprising silicon; and (c) thebase comprising a channel to circulate fluid therethrough, the channelhaving the channel inlet and the channel terminus.
 2. A substratesupport assembly according to claim 1 wherein the ceramic puck comprisesa thickness that is less than 7 mm.
 3. A substrate support assemblyaccording to claim 1 wherein the resistive heating elements are adaptedto be controlled by a controller configured to (i) independently applydifferent electrical power levels to the resistive heating elements,(ii) receive temperature signals from a temperature sensor, and (iii)serve as a feedback control loop to adjust the power applied to theresistive heating elements and the flow of fluid through the channel ofthe base in response to the temperature signals from the temperaturesensor.
 4. A substrate support assembly according to claim 3 wherein theresistive heating elements are powered via independent terminal postswhich extend through the ceramic puck.
 5. A substrate support assemblyaccording to claim 3 wherein the resistive heating elements each have aselected electrical resistance.
 6. A substrate support assemblyaccording to claim 5 wherein the selected electrical resistances arebetween from about 4 to about 12 ohms.
 7. A substrate support assemblyaccording to claim 1 wherein the compliant polymer layer comprisesfibers therein.
 8. A substrate support assembly according to claim 1further comprising a controller configured to: (i) independently applydifferent electrical power levels to the resistive heating elements;(ii) control the temperature and flow rate of fluid passed through thechannel of the base; (iii) receive temperature signals from atemperature sensor; and (iv) serve as a feedback control loop to adjustthe power applied to the resistive heating elements and the flow offluid through the channel of the base in response to the temperaturesignals from the temperature sensor.
 9. A substrate support assemblyaccording to claim 8 wherein the controller is programmed to (i)increase a fluid temperature in the base to a higher level prior toramping up the electrical power levels applied to the resistive heatingelements in the ceramic puck, or (ii) decrease a fluid temperature inthe base to a lower level prior to ramping down the electrical powerlevels applied to the resistive heating elements in the ceramic puck.10. A substrate support assembly comprising: (a) a ceramic puckcomprising: (i) a substrate receiving surface; (ii) an electrode togenerate an electrostatic force to retain a substrate placed on thesubstrate receiving surface; (iii) a plurality of spaced apart resistiveheating elements; and (iv) a backside surface having a plurality ofshaped mesas that are spaced apart from one another and that contact abase, the shaped mesas comprising posts, cones, rectangular blocks, orcylindrical mounds, and wherein the shaped mesas include an array offirst mesas that are adjacent to a channel inlet which is adjacent to aperiphery of the base, and an array of second mesas that are adjacent toa channel terminus, and comprising at least one of: (1) the first mesasare spaced apart a first distance that is larger than a second distancebetween the second mesas; and (2) the first mesas have a first contactregion that is smaller than a second contact region of the second mesas;(b) a compliant layer bonding the ceramic puck to the base, thecompliant layer comprising a silicon material; and (c) the basecomprising a channel to circulate fluid therethrough, the channel havingthe channel inlet and the channel terminus.
 11. A substrate supportassembly according to claim 10 wherein the compliant layer comprises apolymer.
 12. A substrate support assembly according to claim 10 whereinthe resistive heating elements are adapted to be controlled by acontroller configured to (i) independently apply different electricalpower levels to the resistive heating elements, (ii) receive temperaturesignals from a temperature sensor, and (iii) serve as a feedback controlloop to adjust the power applied to the resistive heating elements andthe flow of fluid through the channel of the base in response to thetemperature signals from the temperature sensor.
 13. A substrate supportassembly according to claim 12 further comprising the controller, andwherein the controller is programmed to (i) increase a fluid temperaturein the base to a higher level prior to ramping up the electrical powerlevels applied to the resistive heating elements in the ceramic puck, or(ii) decrease a fluid temperature in the base to a lower level prior toramping down the electrical power levels applied to the resistiveheating elements in the ceramic puck.
 14. A substrate support assemblycomprising: (a) a ceramic puck comprising a substrate receiving surface,the ceramic puck having embedded therein (i) an electrode to generate anelectrostatic force to retain a substrate placed on the substratereceiving surface; and (ii) a plurality of spaced apart resistiveheating elements; (b) a compliant layer bonding the ceramic puck to abase, the compliant layer comprising a silicon material; (c) the basecomprising a channel to circulate fluid therethrough, the channel havinga channel inlet and a channel terminus; and (d) a controller configuredto: (i) independently apply different electrical power levels to theresistive heating elements; (ii) control the temperature and flow rateof fluid passed through the channel of the base; (iii) receivetemperature signals from a temperature sensor; and (iv) serve as afeedback control loop to adjust the power applied to the resistiveheating elements and the flow of fluid through the channel of the basein response to the temperature signals from the temperature sensor, andwherein the controller is programmed to (i) increase a fluid temperaturein the base to a higher level prior to ramping up the electrical powerlevels applied to the resistive heating elements in the ceramic puck, or(ii) decrease a fluid temperature in the base to a lower level prior toramping down the electrical power levels applied to the resistiveheating elements in the ceramic puck.
 15. A substrate support assemblyaccording to claim 14 wherein the compliant layer comprises a polymer.16. A substrate support assembly according to claim 14 wherein theceramic puck comprises a backside surface having a plurality of shapedmesas that are spaced apart from one another and that contact the base,the shaped mesas comprising posts, cones, rectangular blocks, orcylindrical mounds, and wherein the shaped mesas include an array offirst mesas that are adjacent to the channel inlet which is adjacent toa periphery of the base, and an array of second mesas that are adjacentto the channel terminus, and comprising at least one of: (1) the firstmesas are spaced apart a first distance that is larger than a seconddistance between the second mesas; and (2) the first mesas have a firstcontact region that is smaller than a second contact region of thesecond mesas.
 17. A substrate support assembly comprising: (a) a ceramicpuck comprising a substrate receiving surface, an electrode to generatean electrostatic force to retain a substrate placed on the substratereceiving surface, and a plurality of spaced apart resistive heatingelements; (b) a compliant polymer layer bonding the ceramic puck to abase, the compliant polymer layer comprising silicon; (c) the basecomprising a channel to circulate fluid therethrough, the channel havinga channel inlet and a channel terminus; and (d) a controller configuredto: (i) independently apply different electrical power levels to theresistive heating elements; (ii) control the temperature and flow rateof fluid passed through the channel of the base; (iii) receivetemperature signals from a temperature sensor; and (iv) serve as afeedback control loop to adjust the power applied to the resistiveheating elements and the flow of fluid through the channel of the basein response to the temperature signals from the temperature sensor, andwherein the controller is programmed to (i) increase a fluid temperaturein the base to a higher level prior to ramping up the electrical powerlevels applied to the resistive heating elements in the ceramic puck, or(ii) decrease a fluid temperature in the base to a lower level prior toramping down the electrical power levels applied to the resistiveheating elements in the ceramic puck.
 18. A substrate support assemblyaccording to claim 17 wherein the ceramic puck comprises a backsidesurface having a plurality of shaped mesas that are spaced apart fromone another and that contact the base, the shaped mesas comprisingposts, cones, rectangular blocks, or cylindrical mounds, and wherein theshaped mesas include an array of first mesas that are adjacent to thechannel inlet which is adjacent to a periphery of the base, and an arrayof second mesas that are adjacent to the channel terminus, andcomprising at least one of: (1) the first mesas are spaced apart a firstdistance that is larger than a second distance between the second mesas;and (2) the first mesas have a first contact region that is smaller thana second contact region of the second mesas.
 19. A substrate supportassembly according to claim 17 wherein the resistive heating elementsare powered via independent terminal posts which extend through theceramic puck.
 20. A substrate support assembly according to claim 17wherein the resistive heating elements have electrical resistances whichare between from about 4 to about 12 ohms.